Aminoglycoside antibiotics are inexpensive and highly effective, but they can result in cellular injury and apoptosis specific to sensory hair cells of the auditory and vestibular systems. This damage can result in profound and irreparable sensioneural hearing loss. Our laboratory has previously demonstrated that upregulation of heat shock proteins (Hsps) via either heat shock or overexpression of Hsp70 inhibits both aminoglycoside-induced hair cell death and hearing loss. This suggests that induction of heat shock proteins may hold potential as an effective co-therapy aimed at preventing aminoglycoside-induced ototoxicity. However, clinical heat shock therapy is poorly tolerated by patients. Pharmacological induction of Hsps may be a more feasible clinical approach to the protection of aminoglycoside-exposed hair cells. Celastrol is a small molecule that has recently been identified as a pharmacological heat shock protein inducer. Celastrol is a plant extract that has been used safely for many years in Chinese medicine. In addition to modulation of the heat shock response, celastrol also has antioxidant properties. Our preliminary data indicate that celastrol is protective against aminoglycoside-induced hair cell death in the adult mouse utricle in vitro. Similar studies indicate that celastrol also inhibits cisplatin-induced hair cell death, suggesting that celastrol holds promise as a co-therapy aimed at inhibiting ototoxic drug-induced hearing loss. The goals of this project are examine celastrol's effect on apoptotic signaling in hair cells treated with aminoglycoside antibiotics and to begin to examine celastrol's potential as a protective therapy against aminoglycoside-induced hearing loss in vivo. PUBLIC HEALTH RELEVANCE: The aminoglycoside antibiotics are highly efficacious against tuberculosis and multi-drug resistant strains of bacteria. However, these antibiotics have serious ototoxic side-effects that can result in permanent hearing loss. This research program is aimed at developing a co-therapy that will protect the hearing of patients receiving aminoglycoside antibiotic therapy.